1. Field of the Invention
The present invention relates to an image processing apparatus searching for an image processing apparatus connected to a network, the image processing apparatus, a control method, and a storage medium.
2. Description of the Related Art
Conventionally, as a protocol for use in communication with a network device connected to the network (Internet), there has been used IPv4 (Internet Protocol version 4). IPv4 is a protocol located in a network layer defined in the OSI (Open System Interconnection) reference model, and uses 32-bit addresses, defining an address space in which it is used for addressing, routing, error control, etc.
Recently, a problem has occurred that in IPv4 representing the address space by 32 bits, the address space is running short due to an increase in devices connected to networks with the widespread use of the Internet. To solve this problem, IPv6 (Internet Protocol version 6) having an address space expanded to 128 bits has been developed and is being progressively introduced.
In IPv6, the 128-bit address format is composed of two parts: a network address portion formed of the most significant 64 bits and an interface ID formed of the least significant 64 bits. The most significant 64-bit portion is composed of a global routing prefix and a subnet ID.
Differences between three types of addresses, i.e. a stateful address, a stateless address, and a link local address, can be represented by differences between the network address. The stateful address is an IPv6 address acquired from a DHCP server using the DHCPv6 (Dynamic Host Configuration Protocol version 6) protocol. The stateless address is an IPv6 address automatically generated by an IPv6-compatible apparatus based on information sent from a router. The link local address is an IPv6 address that makes communication possible only within a network where the IPv6-compatible apparatus belongs (the same link). Each IPv6-compatible apparatus can have a plurality of addresses of the above-mentioned types bound thereto.
Further, when IPv6 is used, an IPv6-compatible apparatus communicates with a plurality of apparatuses by performing multicast in place of broadcast which has been conventionally performed when IPv4 is used. An IPv6 multicast address is composed of a format prefix (FP) formed by eight bits all set to 1 for indicating that the address is a multicast address, a flag formed by four bits for indicating whether the multicast address is one of multicast addresses permanently assigned by Internet Assigned Numbers Authority (IANA) (when set to 1) or a transient one (when set to 0), four bits indicating a scope indicative of a valid range of the address, and 112 bits indicating a group ID. Consequently, from the leading 4 bytes of an IPv6 address, the scope of an IPv6 multicast address can be known. For example, when the leading 4 bytes of an IPv6 address form FF01, it indicates a multicast address having a scope set to 1, i.e. an interface local scope. When the same form FF02, it indicates a multicast address having a scope set to 2, i.e. a link-local scope, and when the same define FF0E, it shows a multicast address having a scope set to E, i.e. a global scope. Some group IDs are reserved. For example, an SSDP protocol uses C. That is, multicast address set to a link-local scope for use with an SSDP protocol is FF02:0:0:0:0:0:0:C.
On the other hand, there has been proposed a technique concerning device search by a network device management apparatus using an SNMP (Simple Network Management Protocol) in an IPv4 network environment (see Japanese Patent Laid-Open Publication No. 2000-196665). According to Japanese Patent Laid-Open Publication No. 2000-196665, the network device management apparatus transmits broadcast packets to devices connected to a network, and forms a device list. By using subnet broadcast having a network address added to a broadcast address, it is possible to form device lists on a subnet-by-subnet basis.
The subnet broadcast is a broadcast request transmitted to devices that belong to a subnetwork. For example, let it be assumed that a network has a subnet mask of 255.255.255.0 and a network address of 192.168.32.0. In this network, a device transmits a packet to an address of 192.168.32.255 (i.e. a broadcast address) obtained by setting all the bits of the least significant 1 byte to 1. This causes the device to receive responses from all devices existing in the network.
Now, a brief description will be given of an example of the configuration of a network system comprised of a computer and a plurality of devices.
FIG. 19 is a schematic diagram showing an example of the configuration of a network system which is incapable of realizing broadcast by IPv6.
Referring to FIG. 19, the network system is comprised of a personal computer (hereinafter simply referred to as “the PC”) 1901, a server 1902, and a plurality of devices 1903 to 1908. 1909 and 1910 represent routers. For devices within the local network 1911, device search by SNMP broadcast is carried out by an IT (Information Technology) administrator. Further, for devices within a designated network 1912 (beyond the routers), device search by SNMP subnet broadcast 1 and device search by SNMP subnet broadcast 2 are performed.
FIG. 20 is a view showing a device search configuration screen used for performing a device search by an SNMP protocol using IPv4.
Referring to FIG. 20, the device search configuration screen is displayed on a display section of the PC 1901. From the device search configuration screen, “SEARCH LOCAL NETWORK BY IP BROADCAST” 2000 and “SEARCH DESIGNATED NETWORK BY IP BROADCAST” 2001 can be selected as desired as a broadcast search. Further, an IP broadcast address 2002 can be designated.
In the technique disclosed in Japanese Patent Laid-Open Publication No. 2000-196665, however, it is assumed that the device search is performed by SNMP protocol using IPv4, but device search using IPv6 is not taken into consideration. As a consequence, the technique suffers from the problem that it is impossible to designate an IPv6 network address from the server 1902 to search for only IPv6 devices within the network. Further, it suffers from the problem that standard devices belonging to a local network where the server 1902 exists cannot be searched for from the server 1902.